Harold Jellicoe Percival was buried at 11 a.m., the 95th anniversary of the Armistice that ended World War I, the Daily Mirror reported.
Percival never married, and surviving relatives say he spent much of his life backpacking around the country. For the past two years, he had lived in a nursing home in Lytham St. Annes in Lancashire.
The undertaker who arranged the funeral, Eddie Jacobs, placed a death notice in the local paper, asking for veterans and others with military connections to attend. Martin Cooper, a retired police officer, saw the appeal and put it on Facebook, discovering quickly it had gone viral.
Hundreds responded. Percival received full military honors.
"It shows people do care," Jacobs said. "This was a 99-year-old man with only a couple of very distant relatives who as a war hero was going to his last resting place alone. The British people responded like only the British can."
Percival served in the Royal Air Force as ground crew at a Lincolnshire airfield, where his duties included removing the bodies of dead air crew from planes that had been shot up. He was believed to be the last surviving member of the Dambusters unit.
Andre Collyer-Worsell, a great-nephew, said the family had been expecting only a handful of people at the service and found the response overwhelming.
"He was not a hero, he was just someone who did his duty in World War Two, just as his brother and sister did and his father before him in World War One," Collyer-Worsell said.